High Idle Switch: Testing and Inspection
High Idle Switch Diagnosis (with RPO UF3)
Circuit Description
The high idle system is used to provide additional engine power when needed for vehicle accessories. The engine control module (ECM) controls the high idle operation based on various sensor inputs and the high idle switch on the instrument console. This system is not activated by temperatures as is the high idle system for warm up, but the rest of the input and operation are the same. For more information on these parameters, Refer to Manual High Idle System Description.
Diagnostic Aids
If the high idle system is inoperative but the switch circuit works, inspect for the following conditions:
* The high idle switch option is not programmed-Refer to High Idle Switch Programming.
* There are DTCs set-Diagnose these first.
* There is a non-DTC fault in one of the following components or systems:
- The brake switch
- The clutch switch
- The vehicle speed sensor
Test
